e x e c . l i b r a r y FindTask
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¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯REPORT Forbid() missing, unreliable result
SEVERITY Level 2
EXPLANATION If you search for a task by its name, you MUST freeze
multitasking before searching through the public task
list. Otherwise the task could be removed shortly after
you've got the pointer. Any access to the TCB will then
throw Enforcer hits in best case, or it will just trash
memory.
Anyhow, FindTask(NULL) will work fine even with enabled
multitasking. This is because there is no iterating
through the public lists of tasks required to find the
own task, and if you can use the result, you'll surely
be still alive... ;-)
DEADLY In DEADLY mode, this function call will return the
true return code only if multitasking was forbidden
or NULL has been passed as task name. Otherwise it will
return NULL if the task really wasn't there, or
0xFACEDEAD if the task was found. So, just finding out
if this task existed will still work, but accessing it
will cause Enforcer hits.
REMARK Some people claim that this hit is annoying, since they
consider this practice to be legal if you only want to
find out if a port is available or not.
I don't think so. There is still a slight chance to
crash the system. Imagine your program is iterating the
list without Forbid(), looking for a certain Node B
which comes after Node A. Now, while FindPort() is
fetching Node A, a scheduling occurs and another process
gets the processor. This other process now removes Node A
from the list and changes its memory contents. If your
program then gets the processor back, it will get a
completely messed up 'Node A', and will crash.
It is sad, but as long as AmigaOS does not provide a
semaphore mechanism for public lists, we must use Forbid()
if we iterate through them.